Shrimp Virus Report

New, virulent viruses have been documented in foreign shrimp aquaculture,
and evidence suggests that these viruses could cause widespread disease
in shrimp raised in aquaculture and in wild shrimp in the Gulf of Mexico
and southeastern Atlantic coastal regions. To assess the risks associated
with these emerging viral pathogens, the Joint Subcommittee on Aquaculture
(JSA), which is under the auspices of the President's Office of Science
and Technology Policy, formed the interagency Shrimp Virus Work Group.

EPA is making available a qualitative ecological risk assessment describing
the potential risks of nonindigenous pathogenic shrimp viruses on wild
shrimp populations in U.S. coastal waters. Expert conclusions and recommendations
contained in the report are currently undergoing an independent scientific
review. Publication of this draft final report is another in a series
of related activities initiated out of increasing public concerns over
the potential introduction and spread of nonindigenous pathogenic shrimp
viruses to the wild shrimp fishery and shrimp aquaculture industry in
the U.S. Although these viruses pose no threat to human health, outbreaks
on U.S. shrimp farms, the appearance of diseased shrimp in U.S. commerce,
and new information on the susceptibility of shrimp and other crustaceans
to these viruses, prompted the JSA to take action.

The report concludes that viruses could survive in pathways leading to
coastal environments, and that there is potential for viruses to affect
native shrimp in localized areas, such as an estuary or bay. However,
it notes that local populations of shrimp would recover rapidly as a result
of reintroduction of shrimp or increases in reproduction. Although there
was high uncertainty, the report concludes that the risks from viral introductions
to the entire population of native shrimp in U.S. coastal waters is relatively
low. While qualitative evaluations such as these are valuable, the report
concludes that they are associated with a great deal of uncertainty. Therefore,
given the limited information currently available, the report states that
it is not feasible to conduct a more comprehensive, quantitative assessment
of the risks associated with nonindigenous pathogenic shrimp viruses at
this time. The report notes that there is a need to conduct further systematic
research efforts to reduce uncertainty and it identifies a number of priority
research areas.

Cages in Fish Culture

The use of cages in open waters has emerged recently as a fish culture
technology that meets the needs of the industry for large-volume water
supplies at temperatures appropriate to the needs of coldwater species.
Because the cages' structure makes them vulnerable to storm damage, many
concerns have been expressed about the impact of escaped fish on natural
biodiversity and on the integrity of the wild gene pools. Further, unlike
the relatively sterile groundwaters used for most fish hatcheries, the
cages' natural environments expose the fish to natural pathogens that
must be routinely treated with therapeutants and prophylactics-which in
turn are harmful to other elements of the natural biota.

But the most worrisome potential effect of cage aquaculture on wild fish
production is the nutrient enrichment of the surrounding waters via feces
and surplus food. Unlike wastes produced by onshore feedlots and hatcheries
(and cities), these wastes cannot be harvested from the effluents. The
conversion efficiency of fish food to fish is roughly 50 percent. Thus
for every ton of fish produced, there will be about a ton of waste.
If the caged fish are fed on netted lake fish, there may be an effect
on natural populations. If the caged fish are fed on prepared food, the
waste produced represents a new nutrient load to the system. The phosphorus
output from a salmonid cage facility producing 100 tons of fish in the
most efficient way is the equivalent of the raw sewage effluent from a
community of 850 people. Since the industry will seek out relatively sheltered
sites, the list of concerns includes losses of aesthetic and recreational
values, contamination of bottom sediments, and the potential for rising
drinking-water costs.

National
Harmful Algal Bloom Research and Monitoring Strategy: An Initial Focus
on Pfiesteria, Fish Lesions, Fish Kills, and Public Health

"In response to fish lesions, kills, Pfiesteria-like organisms,
and possible threats to public health in the Mid-Atlantic region, the
White House asked federal agencies to develop and coordinate a long-term
national strategy for federally supported research and monitoring on problems
associated with harmful algal blooms (HABs), particularly Pfiesteria
and Pfiesteria-like species." November 1997.

There is growing concern that the crisis in the mid-Atlantic is another
of the increasing number of harmful bloom events that have become a problem
in U.S. coastal waters. In previous work, scientists critically reviewed
the problem and developed a national plan to monitor, assess, control,
and mitigate impacts from HABs. This current strategy builds upon an existing
Federal plan outlined in the report, "Marine Biotoxins and Harmful
Algae: A National Plan"(Anderson et al. 1993), and eight focused
objectives that are identified below.

To protect human health and the environment, immediate support is needed
to:

Isolate, identify, and characterize the microorganisms and their toxins

Develop assays for detection of cells and toxins and improved capabilities
for morphological identification and enumeration

Better understand the impact of the organisms and their toxins on
human health, marine ecosystems, and the economies of coastal areas

Ensure the flow of timely, accurate, and consistent information concerning
HAB events to local managers, professionals, and the general public

To ensure that responsible agencies can respond rapidly and if necessary,
implement effective management and mitigation measures, capabilities need
to be in place to:

Enable Federal and state agencies to respond rapidly through better
support for monitoring, research, and assessment during Pfiesteria
and other HAB events

Maintain and update data bases and information relevant to Pfiesteria
and other HAB events that are easily accessible, reliable and accurate

To support management and mitigation efforts, research must also begin
immediately to:

Explore new and existing technological means to prevent, control,
or mitigate Pfiesteria, related organisms, and other HAB species,
such as improving farm and watershed-scale Best Management Practices
to reduce or eliminate movement of nutrients, sediments, pathogens,
trace elements, and other specific organic compounds to surface and
ground water.

Efforts coordinated under this strategy will complement and augment state
programs, and be implemented through a mix of in-house research and monitoring
and research grants to universities and the states.

EPA Gulf Ecology Division Research

EPA's Gulf Ecology Division (GED) is responsible for research on the physical,
chemical, and biological dynamics of coastal wetlands and estuaries, to
determine ecological condition, evaluate rates and causes of declining
systems, and predict future conditions under various alternative water
quality scenarios. The research program will: (1) Monitor and assess the
ecological condition of coastal wetlands, bays, estuaries, and coral reefs
of the Gulf of Mexico and evaluate the causes of changes: (2) Develop
biological/ecological indicators to (i) classify the ecological status
of coastal wetlands, bays and estuaries, (ii) detect significant change
in ecological status related to chemical contaminants, biotechnology products,
disease, nutrients, energy development, and global warming, and (iii)
identify cause(s) of ecological change, using both reactive (diagnostic
and epidemiologic) and predictive approaches, and (3) Compare ecological
structure and function among microcosms, mesocosms, and field sites to
predict relationships between chemical/stressor exposure and changes in
biodiversity and ecological function. The Division also provides research
and science support to the Gulf of Mexico Program and the Regions and
states.